The environmental impact of major oil spills on marine microorganisms has yet to be thoroughly investigated using molecular biology techniques. The Deepwater Horizon (DWH) drilling rig explosion of 2010 affected an approximately 176,000 km2 surface area of the Gulf of Mexico (GOM) when an estimated 210 million gallons of oil from the Macondo Prospect spilled into the environment. Pelagic Sargassum, a complex of two surface drifting species (Sargassum natans and Sargassum fluitans) of marine brown macroalgae and a critically important habitat in the GOM ecosystem, was suffused by Macondo Prospect 252 oil released during the DWH event. Using 16S rRNA PCR and Roche 454 pyrosequencing, the effect of the oil on the bacterial population associated with pelagic Sargassum and contiguous waters was examined by comparing sequence data generated from samples collected from oiled and non-oiled locations in the northern GOM. Sequence data showed similar microbial composition in Sargassum regardless of exposure to oil primarily dominated by five phyla; Proteobacteria, Bacteroidetes, Actinobacteria, Verrucomicrobia, and unclassified bacteria. The microbial composition in water samples was significantly less diverse than for Sargassum and consisted primarily of Proteobacteria, Firmicutes, and Bacteroidetes. Due to the evenly distributed abundance of microbial species on oiled and non-oiled pelagic Sargassum, study findings indicate that DWH spilled oil had minimal effect on the composition and diversity of the microbial community associated with Sargassum and contiguous waters. However, higher abundances of Sulfitobacter and one species of Psychrobacter were found in oiled water samples when compared to non-oiled water samples indicating some effect of DHW oil in the microbial composition of seawater. Though there are a number of marine studies using molecular biology approaches, this is the first molecular examination of the impact of the DWH oil spill on bacterial communities associated with pelagic Sargassum and contiguous waters from the GOM.
Bibliographical noteFunding Information:
The authors extend their sincere appreciation to the Guy Harvey Ocean Foundation for supporting critical aspects of this research. We acknowledge NOAA Fisheries, Southeast Fisheries Science Center, and SEAMAP for providing funding in support of the ichthyoplankton survey cruise. This study was partially supported by the Gulf of Mexico Research Initiative administered by the Northern Gulf Institute, Mississippi State University, and by the J. Craig Venter Institute. We express our gratitude to the captains and the crew of the R/V Tommy Munro and to Marcia Pendleton for the assistance in sample collection. We thank Tracy Berutti for performing the DNA extractions. We express our appreciation to Mitch Roffer, Greg Gawlikowski, and Matthew Upton (Roffer’s Ocean Fishing Forecasting Service, Inc.; http://www.roffs.com ) for providing satellite imagery/analysis and invaluable advice to assist us in the selection of collection stations. Jason Tilly assisted in developing Fig. . We thank Ben Raines for the use of his underwater photograph of fishes associated with pelagic Sargassum.
© 2016, Springer Science+Business Media New York.
- Gulf of Mexico